1. Field of the Invention
The present invention relates to a lens specifying apparatus that specifies, for example, the lens type, such as a far point importance type, a near point importance type, and a far-near importance type, the maker, and the kind (maker model type) of a subject lens from lens refraction characteristics, such as the refractive power distribution and astigmatism distribution of the subject lens.
2. Description of the Related Art
In recent years, progressive power lenses and far-point aspherical lenses have spread wide as eyeglass lenses. For example, the progressive power lens has a far point portion where the spherical degree does not change and a near point portion where the refractive power changes continuously from the boundary between it and the far point portion. Generally, the far point portion is roughly located on the upper side of the lens center, and the near point portion is offset slightly right and left from the lens center and roughly located on the lower side of the lens. Furthermore, the near point portion and the intermediate portion between the near point portion and the far point portion, which are actually usable, are not provided over the lower portion of the lens, rather extend from the lens center to the lower edge in a relatively narrower width.
However, for the position, configuration, and refractive power variations from the intermediate portion to the near point portion, in the present condition, various types are available in correspondence with the environment in which eyeglasses are used. Also, even in the case of the same type and even in the case of the same maker there are a wide variety of model types.
Therefore, if a person wearing eyeglasses consisting of progressive power lenses of a certain model type wears eyeglasses consisting of progressive power lenses of a different type, there will be cases where a person cannot get accustomed to eyeglasses and will feel usage is poor.
However, since few people memorize the maker and model type of such eyeglasses, it is difficult to select the same lens in the case where a new lens is put in an eyeglass frame when eyeglasses are damaged,
In addition, a multiplicity of eyeglass types have been employed in correspondence with places where eyeglasses are used. For example, there are sport types, driving types, and indoor types (far-near type, intermediate near point type, near point type, far point type, etc.). However, the number of cases where it is unknown which type of eyeglasses is currently used is not few. For example, in the case where eyeglasses currently being used is an intermediate near point type, if the eyeglasses are used in driving a vehicle due to no knowledge of the eyeglass type, there will be cases where the driver will feel eye fatigue. In such a case, it cannot be judged what cause gives rise to eye fatigue.